Sea lice-infection link found during studies

Sea lice can indeed transfer waterborne infections from one fish to another, studies at the Pacific Biological Station in Nanaimo and other research centres suggest.

Scientists attending an international conference on fish health at Vancouver Island Conference Centre last week heard early findings of those studies, which are still at the preliminary stage.

Commercial salmon farmers and environmentalists have long been at odds over whether sea lice associated with fish farms harm wild salmon. Depending what the research uncovers, it could impact rules affecting the aquaculture industry.

Currently Atlantic salmon are reared in the thousands, in open-net pens. Opponents have long been calling for closed containers to prevent sea lice escaping into the ocean, which some believe is responsible for a drop in wild salmon stocks near aquaculture operations.

Advances in pathogen management was the topic discussed by about 150 representatives from government and private interests from as far away as Europe, at the American Fisheries Association’s annual meeting in Nanaimo last week.

One experiment looked at whether pathogens can be spread fish-to-fish by sea lice, by studying fish in aquariums. Results suggest they can.

"You can take one of those lice and move it into (a tank with) fish that have not been infected and there is some evidence you may transfer (pathogens) from fish to fish," said Mark Higgins, Department of Fisheries and Oceans research biologist.

He is cautious to note the studies only prove pathogens can be spread by sea lice, not what really happens in the wild.

"This is all in laboratory conditions with massive doses. You don’t really see that in the environment," Higgins said. "I think the work is really ongoing."